Machining 9 bolt cones
10-22-2009, 07:38 AM
#1
Machining 9 bolt cones
I have a question, I'm about to mill my cones. They are not grooved..they were just kissing the case (one side, the other side was still a wee bit from hitting).
How much do I take off these things? If I take off .010 or so the posi should work again but it still leaves the cones close to the case and next to no clearance in the window. To get them so that I have a good amount of clearance in the window I'll need to mill of anywhere between .075 - .09" and shim it up. What would be wise to do? Machine it off by .05? Don't want to remove too much and reduce spline surface and friction surface.
How much do I take off these things? If I take off .010 or so the posi should work again but it still leaves the cones close to the case and next to no clearance in the window. To get them so that I have a good amount of clearance in the window I'll need to mill of anywhere between .075 - .09" and shim it up. What would be wise to do? Machine it off by .05? Don't want to remove too much and reduce spline surface and friction surface.
10-22-2009, 08:52 AM
#2
Supreme Member
iTrader: (2)
Join Date: Jul 2005
Location: Guilford, Connecticut
Posts: 1,428
Likes: 0
Received 2 Likes
on
2 Posts
Car: 1988 IROC-Z camaro
Engine: 355 TPI
Transmission: tko 500
Axle/Gears: Dana 44 3.31 posi pbr brakes
Re: Machining 9 bolt cones
Basically the idea is to remove as little as possible to get the clearance for the posi to work again. You gotta figure that it took 20+ years for that posi to wear down to the point it was loose and not working. If you mill off a bit of the cone and shim it tight again you should be good for years and years. I only have a hair of clearance myself when i did this but its enough that they are not touching the case and my posi is tight. Taking off too much weakens the cones. I forget what the throwaway measurment is for cones. There is a PDF on google that shows u how much to do and how to shim it tight. Ive posted it many times. Search google for "9 bolt BW posi cone repair".
10-22-2009, 08:59 AM
#3
Re: Machining 9 bolt cones
It only took 70.000 miles to wear them down. The PDF only lists shimming measurements, no posi checking measurements. I'll just take off as little as possible then and shim them up. Will go with .02 or so then. The .01 difference shouldn't matter too much.
10-22-2009, 09:07 AM
#4
Supreme Member
iTrader: (2)
Join Date: Jul 2005
Location: Guilford, Connecticut
Posts: 1,428
Likes: 0
Received 2 Likes
on
2 Posts
Car: 1988 IROC-Z camaro
Engine: 355 TPI
Transmission: tko 500
Axle/Gears: Dana 44 3.31 posi pbr brakes
Re: Machining 9 bolt cones
I honestly dont think there was too much clearance there to begin with. Figure this..whatever you are putting in for shims to get it tight is how much clearance there was between the case and the end of the cones new. I think there was .071 clearance if i remember right when i did mine. I could be completely wrong though.
10-23-2009, 08:38 AM
#5
Re: Machining 9 bolt cones
The cone OD wears down and the housing ID wears out too so the amount you take off and then shim back up is not the clearance that was there from the factory. As the OD wears down the cone goes in deeper and deeper until it hits. .07 sounds about right for the clearance in the window that I see on the 9bolt.com site. Taking that off is way too much though IMO.
Thread
Thread Starter
Forum
Replies
Last Post
New2Chevy
Engine/Drivetrain/Suspension Parts for Sale
2
09-28-2015 12:35 AM
